WAMSI 2 - Dredging Node 3.2.2 - Plume Characterization – Lab Studies

The key objectives of Project 3.2:(1) Characterize the physical/optical properties of sediment suspensions;(2) Map the dredge-generated plume;(3) Provide data to optimize and validate plume modelling;(5) Assess the spatial and temporal variability (~10 years) of background suspended sediment loads using archived remote sensing data;(6) To estimate the benthic light field with respect to TSS;In this study we investigated various common turbidity sensors, including optical scattering and acoustic scattering instrumentation, and compared and contrasted their effectiveness in estimating particle load (TSS concentration), and/or Particle Size Distributions (PSDs). Studies were conducted in a controlled laboratory-based setting with a range of different sediment types primarily obtained from the Pilbara coast.More specifically we: • determined the particle size (PS) of sediment samples from Pilbara coastal waters using a sequoia scientific LISST 100X submersible particle size analyser and related PS to the particulate backscattering slope (γbp parameter) of HobiLabs HydroScat-6 and the particulate scattering slope (γb parameter) of WETLabs acs-176; • Established the relationship between Turb and TSS concentration using the optical properties of particulate backscattering coefficient (bbp), scattering coefficient (bb) and total absorptions (a) from HydroScat-6 and acs-176; Wetlabs ECO NTU and Campbell Scientific OBS3+.